gRPC PHP client HTTP headers - php

Question

I am attempting to set some HTTP headers in a gRPC client call written in PHP. I have read all the documentation I can find for the PHP implementation of gRPC but cannot find anything specifying how to do this in PHP. From reading docs for other languages I have come to think that headers are specified in the client metadata. However, I can't find anything on how these should be formatted in php, and all the formats I try don't seem to work. Here is my current code:
$options = [
'credentials' => $this->credentialsObject,
'update_metadata' => function($metaData){
$metaData['headers'] = ['Authorization' => 'Bearer ' . $this->token];
return $metaData;
}
];
$client = new OrganizationServiceClient($this->url,$options);
$r = new \Google\Protobuf\GPBEmpty();
list($data,$status) = $client->list($r)->wait();
The response I get from that is the same as if I don't set the authorization header at all (Access Denied!), though I have been told that my user should have permission to view that resource.
I don't have access to any server logs to help with debugging on that side (though I am trying to get access to them - might be able to in the next day).
Any help or pointers would be appreciated. I'm been working on this for a few days now and feel like I've tried everything I can think of.
Thanks!

Answer 1

I was able to get the info I needed to solve the problem by asking a question in the grpc.io google group. Here is that thread: https://groups.google.com/forum/#!searchin/grpc-io/php%7Csort:date/grpc-io/p4-P78_EOyY/pHHR6Q5OBwAJ.
The gist of the solution is that gRPC uses HTTP2 (so different header syntax), with metadata being equivalent to headers. Below is my updated code. Here is the important line $metaData['authorization'] = ['Bearer ' . $this->token];. Notice that the $metaData array key is the same as the HTTP2 header key, and the value is an array containing the header value as a string.
$options = [
'credentials' => $this->credentialsObject,
'update_metadata' => function($metaData){
$metaData['authorization'] = ['Bearer ' . $this->token];
return $metaData;
}
];
$client = new OrganizationServiceClient($this->url,$options);
$r = new \Google\Protobuf\GPBEmpty();
list($data,$status) = $client->list($r)->wait();